The present invention relates to a new and distinct cultivar of chrysanthemum plant, botanically known as Chrysanthemum×morifolium Ramat., commercially grown as a garden mum, and herein after referred to by the cultivar denomination ‘Zanmuspar’. ‘Zanmuspar’ is a product of a breeding and selection program for outdoor pot mums (garden mums) which had the objective of creating new chrysanthemum cultivars with a semi-double type flower, a natural season flower date around September 24; blooming for a period of 5 weeks. ‘Zanmuspar’ is a seedling resulting from a crossing of the seed parent id 15.836 and pollen parent id 647. Plants of the new cultivar ‘Zanmuspar’ differ mainly from the parent plants in natural-season flowering. The plants of ‘Zanmuspar’ flower in mid-season, while those of the seed parent flower in early-season, and those of the pollen parent in late-season. The new and distinct cultivar was discovered and selected as a flowering plant by Wilhelmus Bernardus Blom on a cultivated field in Rijsenhout, The Netherlands in 2004. The first act of asexual production of ‘Zanmuspar’ was accomplished when vegetative cuttings from the initial selection in 2004 were propagated further in a controlled environment in Rijsenhout, The Netherlands. The new cultivar has been found to retain its distinctive characteristics through successive propagations.